(a) Field of the Invention
The present invention relates to an assembly structure of an external terminal for a rechargeable battery.
(b) Description of the Related Art
Unlike nonrechargeable batteries, rechargeable batteries may be recharged. Non-aqueous electrolyte rechargeable batteries with high energy density have recently been developed as high power rechargeable batteries. Lower power batteries in which battery cells are made into a battery pack are used as the power source for various portable electronic devices such as cellular phones, laptop computers, and camcorders. Larger battery packs which are formed by connecting several to tens of the rechargeable battery cells may be suitable for motor driven devices such as the electric vehicles.
Rechargeable batteries may be classified into different categories based on external shape such as for example, rectangular box and cylindrical shapes. The rechargeable battery includes an electrode assembly in which a long rectangular-shaped positive plate, a long rectangular-shaped negative plate, and a separator that is interposed between the plates are spiral-wound together. Alternatively, a positive plate, a negative plate, and a separator may be stacked in a multiple layer structure. The electrode assembly is inserted into a container, and a cap assembly is mounted on the container to form the battery.
The cap assembly of such rechargeable batteries has an external terminal that is coupled with the electrode assembly which is fixed to the container by welding, etc. to seal the container.
Generally, the external terminal of the cap assembly is inserted into a hole that is formed on the cap plate of the cap assembly. Then, a packing and an O-ring are disposed between the hole and the external terminal to provide electrical insulation and a tight fit.
The external terminal is coupled with the cap plate by a nut that is fastened to a screw thread that is formed on the outer circumference of the external terminal. The packing and O-ring are pressed by the tightness of the nut to seal the hole.
However, the above sealing structure and installation of the external terminal is problematic because it requires many parts which raises the manufacturing cost, and complicates the manufacturing process to decrease the manufacturing efficiency.